Natural Gas: A “Bridge” to Long Term Reliance on Fossil Fuels

By Amelia Schlusser, Staff Attorney

Once we construct new natural gas infrastructure, we will
continue to use it for decades. Credit: SASOL

Electricity generation from natural gas-fired power plants more than doubled between 2000 and 2012. The U.S. Energy Information Administration’s Annual Energy Outlook 2015 projects that natural gas-fired generation will increase by 40% between 2013 and 2040. Because natural gas emits less carbon dioxide than coal, some commenters and analysts have asserted that the increased reliance on natural gas for electricity generation will help reduce U.S. greenhouse gas emissions while we transition to a renewable energy grid. Until recently, the data appeared to back up this assertion: between 2007 and 2013, U.S. energy-related CO₂ emissions fell by approximately 11%. While a number of factors contributed to this decline, the shift from coal to natural gas was widely assumed to be the single biggest contributor. However, a new study in the journal Nature Communications found that these emissions reductions were primarily due to reduced energy consumption stemming from the 2008 economic downturn.

The study’s authors reviewed economic and emissions data from 1997 to 2013 and found that economic growth and recession were the primary factors influencing U.S. emissions during the 16-year period. ClimateWire reported that 83% of the emissions reductions occurring between 2007 and 2009 were caused by “[c]hanges in the type and amount of goods consumed and produced in the United States.” Outsourcing U.S. manufacturing to developing countries also contributed to decreases in emissions. Overall, the shift from coal to natural gas only caused emissions to decrease by 1.2%.

The Nature Communications study raises some serious questions regarding the actual climate benefits of switching from coal to natural gas, and casts further doubt on the potential for natural gas to provide a “bridge” to a renewably powered energy system. The general premise behind the theory of natural gas as a bridge fuel relies on the idea that natural gas emits less CO₂ than coal. Therefore, bridge theory proponents contend, we should invest in natural gas resources in the short term while we wait for renewable energy costs to drop in the long term. If, however, shifting from coal to natural gas-fired electricity will not significantly reduce power sector carbon emissions, the bridge theory starts to crumble. This is because transitioning from coal to natural gas requires substantial investments in new generating facilities and related infrastructure, such as natural gas pipelines. Once these facilities are constructed, they will remain in operation for many years while investors gradually recover the resources’ capital costs from electricity users. Rather than carry us towards a renewably powered future, the so-called bridge would actually lock in carbon emissions for decades.

Rather than build a risky natural gas bridge that may lead us right back where we started, we should focus on building a resilient, sustainable energy system powered by renewables, energy storage, efficiency, and demand-side management. The transition to a sustainable, carbon-free energy grid will take time and effort, but each individual component will take us one step closer to where we want to go.